Live center for lathes, grinders and the like



Oct. 18, A. STORM ET AL 1,883,075

LIVE CENTER FOR LATHES, GRINDERS, AND THE LIKE Filed Feb. 18, 1931Patented Oct. 18, 1932 UNITED STATES PATENT OFFICE ADOLPH STORM AND THORTHORSEN, OF MINNEAPOLIS, MINNESOTA, ASSIG'NORS T0 STORM MANUFACTURINGCO., ING., OF MINNEAPOLIS, MINNESOTA, A CORPORATION k0E MINNESOTA .Y

LIVE CENTER non LATHES, GEINDEES AND THE LIKE Application led February18,* 1931. Serial No. 516,650.

Our present invention has for its object the provision of a simple andhighly eiiicient live center for lathes, grinders and the like, intendedfor general use but especially de-` signed for use in connection with adead center for holding a piston or other cylindrical body during thefinishing thereof.

This invention, in part, is a division of our'pending application filedMarch 21st, 1930, under Serial No. 437,741 and entitled Piston turningand grinding machine.

Generally stated, the invention consists of the novel devices andcombinations of devices hereinafter described in the claims.

In the accompanying drawing, which illustrates4 the invention, likecharacters indicate P like parts throughout the several views.

Referring to the drawing:

Fig, 1 is a fragmentary front elevation of a lathe having the inventionembodied therein, and also showing in the lathe a piston by means ofbroken lines;

Fig. 2 is a view principally in section taken on the line 2-2 of Fig. 1,on an enlarged scale;

Fig. 3 is the face view of the live center with some parts sectioned onthe line 3*-3 of Fig. 2; and

Fig. 4 is a. fragmentary detail view with some parts sectioned on theline 4-4 of Fig. 3. Y

The invention is shown applied to a lathe especially designed for use innishing pistons for internal combustion engines, and of the parts of thelathe, the numeral 5 indicates the bed, 6 the headstock, 7 thetailstock,8 the driven live center spindle, and 9 the dead center carried by a bar10, mounted in the tailstock 7 in axial alignment with the vspindle, 8for end-wise sliding movement toward or from said spindle, and heldwhere ad'usted by a clamp 11.

eferring now in detail to the live center 12, the body 13 thereof is inthe form of a truncated cone, having on its base at the axis thereof ahub 14 applied to the inner end of the spindle 8 to which it isrigidlybut detachably secured by screw threads. In the face of the body 13 is alarge relatively deep annular recess 15. Formedwith body 13 within itsrecess 15, is a pair ofV diametrically opposite driving lugs 16. Alsoformed with the body 13, at the axis thereof and projecting into therecess 15, is a raised spherical bearing surface 17.

A piston X is shown held inthe lathe by the centers 9 and 12, and whichpiston is provided with the customary internal bosses Y, which surroundthe seats therein for the Wrist pin Z.

When the piston X is held by the centers 9 and 12, the outer edge of itsskirt loosely bears against the conical bearing surface of thelivecenter 12 and is heldpressed there against by the dead center 9, theconical oint of which extends into a seat therefor in the head of saidpiston. VAt the time the dead center 9 is brought into contact with thehead of the piston X and said piston pressed against the conical bearingsurface of the live center 12, said piston, by its loose contact withsaid conical bearing surface, will self-adjust itself thereon and bebrought into true axial alignment with the axes of the centers 9and 12.

To cause the piston X to rotate with the f live center 12, said centeris provided with a U-shaped driving dog. The driving dog 18 is mountedin the recess 15 over the bearing surface 17 with its prongs extendingoutward thereof and is connected tothe body 13 by a stud 20 whichloosely extends through a relatively large hole in the hub 19 at theaxis thereof. f This stud 20 is mounted in a bore` in the live center12, at the axis thereof, rigidlysecured thereto by a press t and extendsoutward-through the recess 15.

The driving dog 18 is detachably secured to the stud 2O by a frictionlock 21 that comprises an annular lock groove in said stud and a springpressed ball mounted in a seat in the driving doge18 and extends intosaid lock groove. To hold the ball of the friction lock 21 in its seatwhen the driving dog 18 is removed from the stud 20 said seat iscontracted. It is important to note, by reference to Fig. 4, that theposition of the lock groove on the stud 20 is such that the frictionball, which is spring pressed therein, holds the hub 19 axially spacedfrom the the driving dog 18 to rock on the stud 20, fory a purpose thatwill presently appear. Under extreme rocking movements ofthe driving dog18 on the stud 20 the same will engage the bearing surface 17. v

The hub 19 of the driving dog 18 is substantially entirely within therecess 15, and

extends between the driving lugs 16 for a lim-Y ited pivotal movement,in respect thereto, about the axis of the stud 2O (see Fig. 3). Theengagement of the driving lugs 16 with the driving dog 18 will drivesaid dog in the same direction with the live center 12. As theconnection between the driving dog 18 and the driving lugs 16 is loose,said connec tion does not interfere with the self-adjust ment of thedriving dog 18 in respect to the live center 12.

W'hen the piston X is held by the centers 9 and 12, the prongs of thedriving dog 18 extend into said piston and straddle the wrist pin Z forcontact with the bosses Y at opposite sides thereof, and form aconnection between the live center 12 and piston X to cause said pistonto turn with the live center 12 The purpose of the wabbled oint, betweenthe driving dog 18 and live center 12, is to permit said dog toself-adjust itself in respect to the live center 12 so that both prongsof the driving dog 18 will engage the bosses Y. The necessity of thisself-adjustment of the driving dog 18 in respect to the live center 12,is that the bosses Y are often out of axial alignment, uneven and varyin thickness and formation.

'Ihe object of the recess 15 in the body 13 is to receive the transverseportion of the driving dog 18 and form a compact structure, and give asmuch clearance as possible between the stud 20 and wrist pin Z, for thereason that in certain pistons their wrist pins are relatively close tothe outer edges of the skirts thereof and would interfere with theengagement of said skirt with the live center.

From what has been said, it will be understood that the inventiondescribed is capable of modifications as to detail of construction andarrangement within the scope of the invention herein disclosed andclaimed.

What we claim is:

1. In a device of the class described, a body having on its face aconical bearing surface, a recess in said face at the axis thereof, saidbody having in said recess a pair of diametrically opposite drivinglugs, and a U- shaped driving dog, the transverse portion of which ismounted in said recess between lthe driving lugs with its outer facebetween the prongs substantially in the same plane with the outer edgeof said surface, and a wobbled joint connecting the driving dog to thebody with freedom to turn about the axis thereof between the drivinglugs.

2. In a device of the class described, a body having on its face aconical bearing surface,

a recess in said face at the axis thereof, and.

a U-shaped drivingdog the transverse portion of which is mountedin saidrecess with its outer face between the prongs substantially intheV sameplane with the outer edge of said surface, `and a wobble jointconnecting the dog` to thebody.

3'. In a device of the class described, a body having on its face aconical bearing surface,a forwardly projecting fixed stud at its axisand a pair of diametrically opposite driving lugs, said stud being roundin cross sectiony and having intermediate of its ends acircumferentially extended annular lock groove, a U-shaped driving dogextending between tlie driving'lugs and having at its axis a borethrough which said stud extends and supports the driving dogA withfreedom to turn thereon between the driving lugs, and a spring-pressedfriction member mounted on the driving dog and extending into the lockgroove with freedom for circumferential movement therein, the diameterof the bore in the driving dog being of suflicient size to permituniversal wobbling movement of the driving dog on the stud about theaxis thereof, said lock groove and cooperating member being arranged tohold the driving dog on the stud spaced from the body to permit saidwobble movement of the driving dog.

4:. The structure defined in claim 3 which further includes positivemeans, between the body and driving dog at the axis thereof, andarranged to prevent the driving dog from being forced axially againstthe body.

5. In a device of the class described, a body having on its face aconical bearing surface, a recess in said face at the axis thereof, abore at the axis of said recess, a boss on the body surrounding the boreand extending into the recess, a pair of diametrically opposite drivinglugs in the recess and a fixed stud in Y the driving dog and extendinginto the lockl groove with freedom for circumferential movement therein,the diameter of the bore inthe driving .dog being of suflicient size topermit universal wobbling movement of the driving dog on the stud aboutthe axis thereof, said lock groove and cooperating member being arrangedto hold the driving dog on the stud.

In testimony whereof We affix our signatures.

ADOLPH STORM.. THOR THORSEN.

